Simultaneous distillation-extraction: preparative recovery of volatiles under mild conditions in batch or continuous operations

In a previous publication, a preparative apparatus was developed and optimi zed for simultaneous distillation-extraction (SDE) based on a theoretical m odel. In this paper, its performances were tested under various working con ditions using a model mixture of flavourings. Separations were achieved at boiling water temperature as well as under mild conditions, which reduce ar tefact formation (room temperature, reduced pressure). High recoveries were obtained for batch experiments, but the boiler can also be fed from an ext ernal tank for continuous operations. This permits consideration of the pre parative isolation of volatiles on a laboratory scale for subsequent fracti onation and analysis, as well as industrial scale operations. Examples are given for real food flavours: one-step preparation and isolation of a react ion flavour, isolation of yoghurt and coffee flavourings, recovery of natur al benzaldehyde from wastewater. In addition, the use of a food-grade solve nt to achieve SDE isolation yields an 'edible' extract which can be reincor porated into a food without elimination of the solvent. (C) 1998 John Wiley & Sons, Ltd.